Differential toxic effect of cis-platinum(II) and palladium(II) chlorides complexed with methyl 3,4-diamine-2,3,4,6-tetradeoxy-α-L-lyxo-hexopyranoside in mouse lymphoma cell lines differing in DSB and NER repair ability

The aim of this work was to test the cytotoxicity of newly synthesized cis-type complexes of platinum(II) and palladium(II) dichloride with methyl 3,4-diamine-2,3,4,6-tetradeoxy-α-L-lyxohexopyranoside, [M(C₇H₁₆ N₂O₂)Cl₂]·H₂O, against two mouse lymphoma cell lines (L5178Y) differing in their double strand breaks and nucleotide excision repair ability. cis-Diaminedichloroplatinum (CDDP) was used as a reference compound. The toxicity of Pt(C₇H₁₆N₂O₂)Cl₂ appeared to be similar for both cell lines: IC₅₀ is 8 μM for L5178Y-R cells and 12 μM for L5178Y-S cells, respectively. In contrast, the palladium complex was found to be more toxic for the LY-R cells than for the LY-S cells. The cytotoxicity of both compounds was compared with their ability to induce DNA crosslinks, as measured by the modified comet assay. CDDP caused retardation of the DNA migration induced by 2 Gy of the X-irradiation in a dose-dependent manner. The ability of Pd(C₇H₁₆N₂O₂)Cl₂ to retard X-ray induced DNA migration was more pronounced than its platinum analogue and CDDP (see Fig. 6). However, this was not reflected in the toxicity of the compound. Such results indicate that these two compounds may cause a different type of DNA damage and/or that the DNA damage caused by the palladium(II) compound was dealt with in a different manner from that induced by the platinum(II) complex.